Optimizing learning of scientific category knowledge in the classroom: the case of plant identification.

Learning to identify organisms is extraordinarily difficult, yet trained field biologists can quickly and easily identify organisms at a glance. They do this without recourse to the use of traditional characters or identification devices. Achieving this type of recognition accuracy is a goal of many courses in plant systematics. Teaching plant identification is difficult because of variability in the plants' appearance, the difficulty of bringing them into the classroom, and the difficulty of taking students into the field. To solve these problems, we developed and tested a cognitive psychology-based computer program to teach plant identification. The program incorporates presentation of plant images in a homework-based, active-learning format that was developed to stimulate expert-level visual recognition. A controlled experimental test using a within-subject design was performed against traditional study methods in the context of a college course in plant systematics. Use of the program resulted in an 8-25% statistically significant improvement in final exam scores, depending on the type of identification question used (living plants, photographs, written descriptions). The software demonstrates how the use of routines to train perceptual expertise, interleaved examples, spaced repetition, and retrieval practice can be used to train identification of complex and highly variable objects.

Inflorescences: concepts, function, development and evolution.

BACKGROUND: Inflorescences are complex structures with many functions. At anthesis they present the flowers in ways that allow for the transfer of pollen and optimization of the plant's reproductive success. During flower and fruit development they provide nutrients to the developing flowers and fruits. At fruit maturity they support the fruits prior to dispersal, and facilitate effective fruit and seed dispersal. From a structural point of view, inflorescences have played important roles in systematic and phylogenetic studies. As functional units they facilitate reproduction, and are largely shaped by natural selection. SCOPE: The papers in this Special Issue bridge the gap between structural and functional approaches to inflorescence evolution. They include a literature review of inflorescence function, an experimental study of inflorescences as essential contributors to the display of flowers, and two papers that present new methods and concepts for understanding inflorescence diversity and for dealing with terminological problems. The transient model of inflorescence development is evaluated in an ontogenetic study, and partially supported. Four papers present morphological and ontogenetic studies of inflorescence development in monophyletic groups, and two of these evaluate the usefulness of Hofmeister's Rule and inhibitory fields to predict inflorescence structure. In the final two papers, Bayesian and Monte-Carlo methods are used to elucidate inflorescence evolution in the Panicoid grasses, and a candidate gene approach is used in an attempt to understand the evolutionary genetics of inflorescence evolution in the genus Cornus (Cornaceae). Taken as a whole, the papers in this issue provide a glimpse of contemporary approaches to the study of the structure, development, and evolution of inflorescences, and suggest fruitful new directions for research.

Image use in field guides and identification keys: review and recommendations.

BACKGROUND AND AIMS: Although illustrations have played an important role in identification keys and guides since the 18th century, their use has varied widely. Some keys lack all illustrations, while others are heavily illustrated. Even within illustrated guides, the way in which images are used varies considerably. Here, we review image use in paper and electronic guides, and establish a set of best practices for image use in illustrated keys and guides. SCOPE: Our review covers image use in both paper and electronic guides, though we only briefly cover apps for mobile devices. With this one exception, we cover the full range of guides, from those that consist only of species descriptions with no keys, to lavishly illustrated technical keys. Emphasis is placed on how images are used, not on the operation of the guides and key, which has been reviewed by others. We only deal with operation when it impacts image use. MAIN POINTS: Few illustrated keys or guides use images in optimal ways. Most include too few images to show taxonomic variation or variation in characters and character states. The use of multiple images allows easier taxon identification and facilitates the understanding of characters. Most images are usually not standardized, making comparison between images difficult. Although some electronic guides allow images to be enlarged, many do not. CONCLUSIONS: The best keys and guides use standardized images, displayed at sizes that are easy to see and arranged in a standardized manner so that similar images can be compared across species. Illustrated keys and glossaries should contain multiple images for each character state so that the user can judge variation in the state. Photographic backgrounds should not distract from the subject and, where possible, should be of a standard colour. When used, drawings should be prepared by professional botanical illustrators, and clearly labelled. Electronic keys and guides should allow images to be enlarged so that their details can be seen.

Principles of visual key construction-with a visual identification key to the Fagaceae of the southeastern United States.

BACKGROUND AND AIMS: Advances in digital imaging have made possible the creation of completely visual keys. By a visual key we mean a key based primarily on images, and that contains a minimal amount of text. Characters in visual keys are visually, not verbally defined. In this paper we create the first primarily visual key to a group of taxa, in this case the Fagaceae of the southeastern USA. We also modify our recently published set of best practices for image use in illustrated keys to make them applicable to visual keys. METHODOLOGY: Photographs of the Fagaceae were obtained from internet and herbarium databases or were taken specifically for this project. The images were printed and then sorted into hierarchical groups. These hierarchical groups of images were used to create the 'couplets' in the key. A reciprocal process of key creation and testing was used to produce the final keys. PRINCIPAL RESULTS: Four keys were created, one for each of the parts-leaves, buds, fruits and bark. Species description pages consisting of multiple images were also created for each of the species in the key. Creation and testing of the key resulted in a modified list of best practices for image use visual keys. CONCLUSIONS: The inclusion of images into paper and electronic keys has greatly increased their ease of use. However, virtually all of these keys are still based upon verbally defined, atomistic characters. The creation of primarily visual keys allows us to overcome the well-known limitations of linguistic-based characters and create keys that are much easier to use, especially for botanical novices.

Early floral development of Heliconia latispatha (Heliconiaceae), a key taxon for understanding the evolution of flower development in the Zingiberales.

We present new comparative data on early floral development of Heliconia latispatha, an ecologically and horticulturally important tropical plant within the order Zingiberales. Modification of the six members of two androecial whorls is characteristic of Zingiberales, with a reduction in number of fertile stamen from five or six in the banana families (Musaceae, Strelitziaceae, Lowiaceae, and Heliconiaceae) to one in Costaceae and Zingiberaceae and one-half in Marantaceae and Cannaceae. The remaining five infertile stamens in these later four families (the ginger families) are petaloid, and in Costaceae and Zingiberaceae fuse together to form a novel structure, the labellum. Within this developmental sequence, Heliconiaceae share with the ginger families the possession of an antisepalous staminode, a synapomorphy that has been used to place Heliconiaceae as sister to the ginger family clade. Here, we use epi-illumination light microscopy and reconstruction of serial sections to investigate the ontogeny of the Heliconia flower with emphasis on the ontogeny of the staminode. We compare floral development in Heliconia with that previously described for other species of Zingiberales. A comparison of floral structure and development across Zingiberales is presented to better understand the evolution of the flower in this charismatic group of tropical plants.

Epi-illumination microscopy coupled to in situ hybridization and its utility in the study of evolution and development in non-model species.

Evolutionary developmental biology often combines methods for examining morphology (e.g., scanning electron microscopy, SEM) with analyses of gene expression (e.g., RNA in situ hybridization). Due to differences in tissue preparation for SEM and gene expression analyses, the same specimen cannot be used for both sets of techniques. To aid in the understanding of morphological variation, it would be particularly useful to have a high-magnification image of the very same sample in which gene expression is subsequently analyzed. To address this need, we developed a method that couples extended depth of field (EDF) epi-illumination microscopy to in situ hybridization in a sequential format, enabling both surface microscopy and gene expression analyses to be carried out on the same specimen. We first created a digital image of inflorescence apices using epi-illumination microscopy and commercially available EDF software. We then performed RNA in situ hybridizations on photographed apices to assess the expression of two developmental genes: Knotted1 (Kn1) in Zea mays (Poaceae) and a PISTILLATA (PI) homolog in Musa basjoo (Musaceae). We demonstrate that expression signal is neither altered nor reduced in the imaged apices as compared with the unphotographed controls. The demonstrated method reduces the amount of sample material necessary for developmental research, and enables individual floral development to be placed in the context of the entire inflorescence. While the technique presented here is particularly relevant to floral developmental biology, it is applicable to any research where observation and description of external features can be fruitfully linked with analyses of gene expression.